The invention relates to an apparatus for controlling the deposition of feed material on a deposition build-up surface of a feed arrangement for feeding feed material from an in-process feed material source to a material handling location.
Stokers are mechanical devices that feed and burn solid fuels in a bed at the bottom of a furnace. The solid fuel is burned on some form of grate, through which passes some or all of the air for combustion. The grate surface in the stationary or moving. Feeder devices continuously project metered amounts of solid fuel into the furnace above an ignited fuel bed on the grate. Fines are burned in suspension while larger particles fall and burn on the grate.
A particular type of coal feeder device for feeding metered amounts of coal from a coal silo onto a stoker includes an underthrow coal distributor having a spaced chain that conveys substantially uniform increments of the coal fed thereto from the coal silo. The spaced chain drops off the coal to fall in between respective pairs of the rotating blades of a distribution rotor and the distribution rotor further conveys the coal to the stoker, which may be, say, a traveling grate stoker.
It has become a common design practice, in connection with this type of coal feeder device, to provide a so-called siftings tray shortly below the lower run of the spaced chain of the underthrow coal distributor and extending to the upstream edge of a cowling partially encircling the distribution rotor. Such siftings trays are subjected to a deposition build-up of coal particles thereon in connection with which an excessive build up of such coal particles interferes with the operation of the spaced chain of the underthrow coal distributor.
While one approach to the deposition build-up of coal particles has been to merely permit such a build-up of the coal particles, whereupon space constraints the inherent instability of the accumulation of the coal particles will eventually limit further deposition build-up of coal particles, the need still exists for an approach that can more reliably ensure the desired operation of the underthrow coal distributor. Such an approach should preferably be inexpensive to manufacture and should be capable of using a power source that is readily available in a typical process plant, in order to keep installation costs to a minimum. Also, the approach should be suitable for use in the relatively harsh environment of the coal feed operation including being subjected to temperature gradients and vibration. The system also should be simple and reliable, in order to keep maintenance costs to a minimum.
Accordingly, it is an object of the present invention to provide an apparatus that addresses the concerns set forth above.